local function map(a, f)
	for i = 1, #a do
		a[i] = f(a[i])
	end
	return a
end
local prefix = "[DEBUG]"
local function printlist(a)
	local c = table.concat(a, ", ")
	local s = string.format("%s {%s}", prefix, c)
	print(s)
end
local function test()
	local a = map({1, 2, 3}, function(e)
		return e * 2
	end)
	printlist(a)
end
test()
